When multiple reservoirs are produced through a common facility network, the capability to integrate the modeling of surface and subsurface can be critical to field development and optimization. The shared facility network imposes constraints that the combined production cannot exceed, determines the pressure drop in the flow lines, and the composition and volume of the sales and reinjection streams. Pressure drop in flow lines is particularly important in deepwater field development, where flow lines are long, and production from multiple reservoirs can flow through the same riser.
Often, the fluid characterizations of these reservoirs have been derived independently. In each case, the appropriate fluid representation was selected that provided an optimum combination of accuracy and computational efficiency. The two most common fluid characterizations are the equation of state (EOS) model and the black oil model.
A hydrocarbon fluid may actually be composed of hundreds of distinct components. When modeling using an EOS, the engineer must specify the number of pseudo-components (typically 5 to 12) and their EOS properties. Pseudo-components are combinations of actual components. Alternatively, black-oil modeling involves specification of a number of common engineering measurements in tables that vary with pressure. However, it is inherently a model with two pseudo-components. The net result is that the different connected reservoirs are being modeled with a variable number of pseudo-components, some of which may be common. However, even the common pseudo-components may have different fluid properties in the different reservoirs.
While a myriad of papers have been written about matching a single fluid, almost none have been devoted to matching a set of fluids. In most cases, the authors have tried to match multiple fluids with a single EOS model. In rare cases, they have matched the fluids with the same component set, but allowed the components to have different properties. For example, one popular approach is to have the fluids have the same components and the same properties, but different amounts of each component. However, this approach is useful only when the fluids are related in some way, for example, fluids in a gas cap or associated oil rim within the same petroleum reservoir.
The illustrated figures are only exemplary and are not intended to assert or imply any limitation with regard to the environment, architecture, design, or process in which different embodiments may be implemented.